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Full text of "The Cambridge Natural History"

AMERICAN    DIPROTODONTS

I29

is one strong pair, with occasionally one or two rudimentary incisors.

FIG, 63.—Skull of Wombat (Phascolomys wombat). (Lateral view.) ang, Angular pro-
cess ; cond, condyle of mandible ; ext.aud, opening of bony auditory rneatus ;
ex.oc, exoccipital; ju, jugal j Icr, lacbrymal; max, maxilla j nas, nasal; p.tnax,
premaxilla ; sq, squaincsal; ty^ tympanic. (From Parker and Haswell's Zoology.}

The upper canines, if present, are not large. The molars are
tuberculate or ridged. All Marsupials (ex-
cept the Wombats) to some extent, and the
Macropods especially, are characterised by
the prolongation of the tubes of the dentine
into the clear enamel. The significance of
this fact is, however, lessened by the fact
that the same penetration of the enamel
by dentinal tubes occurs in the Jerboa, the
Hyrax, and some Shrews. The feet have
two syndactylous toes,1 less marked in the
"Wombats than in the Kangaroos and
Phalangers.

This order is mainly Australian at the
present day, using the term, of course in
the " regional" sense (see p. 84); the only
exception indeed to this statement is the
occurrence of the genus Caenolestes in South Fra e4._Bones of right

America. IB at it is now known that Dipro-
todont Marsupials formerly existed in the
same part of the world.

Fain. 1. Macropodidae.—This family
contains the Kangaroos, Wallabies, Kat-
Kangaroos, and Tree-Kangaroos. With the exception of Xtendro-

1 Except in the South Am«ricau Diprotodonts.
VOL. X

foot of Kangaroo (Macro-
j&tis fannetti). a, Astra-
galas ; c, calcaneuin ;
eft, cuboid ; e3, ento-cu-
neiform ; nt navicular;
JI- V, second to fifth, toes.
(From Flower's Osteology,}